Color change apparatus



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E R was SQN %N 553 )QQWQ WSQIL I NI I I I! IIIIIIIIIIII I I. I I II w Am m K D m H R E ilnited States Patent C) 3,450,092 COLOR CHANGEAPPARATUS Erhard Keck, Toledo, Ohio, assignor to The De Vilbiss Company,Toledo, Ohio, a corporation of Ohio Filed July 8, 1965, Ser. No. 470,497Int. Cl. B05c 11/00 U.S. Cl. 118-2 15 Claims ABSTRACT OF THE DISCLOSUREAn apparatus including a spray gun for selectively depositing one of aplurality of fluid coating materials upon objects to be coated. Theapparatus includes a pneumatically controlled pressure regulatorelfective to provide a relatively low fluid pressure for the coatingmaterials and pneumatic control means to override the pressure regulatorto cause a relatively high fluid pressure when a solvent is used topurge the system prior to change from one of said materials to another.

This invention relates to an apparatus for controlling a spray device tofacilitate deposition of coating materials of varying kind. Moreparticularly, the invention is concerned with an apparatus that willenable a spraying device to sequentially discharge differently coloredliquid coating materials. However, the invention is equally appli cableto instances in which the difference between successively sprayedcoating materials is one of another nature such as a diflerence inviscosity. The invention is also useful where it is desired momentarilyto increase the pain discharge as, for example, to clear a partiallyclogged spray gun.

At the present time the spraying of various colors of paints or the likeis done largely with separate spray guns, one for each color, or withone gun that is adapted for rapid connection and disconnection to hosescarrying separate colors of paint. Attempts have been made to pro vide aremotely controlled apparatus which will feed separate colors to asingle spray gun and which will also permit the operator to clean thespray gun by passing a solvent through it as a part of the color changecycle. The patents to Fleming, 2,257,004, and Herklotz et al.,3,145,930, show apparatus of this general class.

It is desirable that a color change apparatus be fast enough to completea color change in the interval between the passage of successivearticles to be sprayed which are hung on a conveyor traveling at anormal speed. This time interval may amount to only a few seconds.Further, the apparatus must require a minimum of judgment and dexterityon the part of the operator so that mistakes can be avoided, as far aspossible, to eliminate improperly sprayed parts. Not only must the colorchange apparatus operate rapidly, but it must also be flexible enough totake into account the various problems that arise by reason of thechange in characteristics of successively sprayed materials.

An apparatus which uses a single gun for spraying a plurality of colorsor kinds of liquids usually requires a flushing period during which theremaining residue of the terminated liquid is purged from the common gunby a solvent prior to initiation of spraying the second liquid. However,it has been found that under many conditions this quantity of terminatedliquid is so small that only a very short purge is required.

The change of color, even when including a solvent purge, can be mademore rapidly if provision is made for increasing the pressure on thesprayed liquid during the time in which the conduit to the spray gun isbeing flushed and filled with the new color. This is accomplished in theapparatus disclosed in the Herklotz et al. patent referred to above byincreasing the speed of rotation of a centrifugal paint supply pumpduring the color change and dropping the speed back to normal when thechange is complete. In most installations in this country, the use amechanically driven metering type paint supply pump is avoided, andpaint is fed to the spray gun from a pressure pot in which the paint orliquid coating material is held under a predetermined pressure imposedby pressurizing the air in the paint container or from a paintcirculating system in which a constant pressure is held on the paint.The present invention is adapted to a substantially constant pressurepaint supply system.

In the following description and discussion the word fluid is used todesignate a liquid coating or flushing material, and the word air isused whenever a gaseous medium is referred to.

In accordance with the present invention, the pressure at which fluidpasses to and out of the spray gun is controlled by an easilycontrollable air pressure. As the air pressure is increased, the fluidpressure is likewise increased automatically.

While spraying proceeds normally with the fluid coating materialsupplied to the spray gun at a predetermined low pressure of, forexample, 5 to 7 p.s.i., a fluid pressure regulator valve at the spraygun receives control air at this pressure from a control regulator. Whenthe color change is to be made, or the system is to be flushed, thepresent invention includes a fluid pressure control override by whichthe control air is caused to pass to the fluid regulator at the spraygun under a substantially increased pressure of, for example, 25 to 30p.s.i. The increase in pressure on the fluid regulator valve permitsfluid at a correspondingly increased pressure to pass through the fluidconduits and out of the spray gun from the pressurized sources abovementioned..It will be seen that so long as the source pressure ismaintained above any pressure that might be desirably used at the spraygun, pressure fluctuation at this point will not afl ect the system inany way since reguation takes place at the regulator valve which isnormally very close to the spray gun itself.

If the spraying system is to be used with the customary volatile andflammable solvents, it becomes desirable to eliminate from the sprayzone or spray booth, so far as possible, all electrical relays, switchesand other devices in which sparking may occur. To comply with safetyrequirements any such devices located in the spray Zone must be of anapproved explosive-proof construction and requires special installation.To avoid this significant increase in the expense of an installation,the present invention utilizes pneumatically actuated valves andcontrols throughout the spray zone and is thus economical. In someinstallations, remotely located electrical devices may be tolerated solong as they are not in or near the spray booth or spray zone where amist of flammable liquid may be found.

As previously noted, it is desirable that the system be so arranged thatthe flow of solvent or flushing fluid be started promptly after thetermination of the flow of the existing color at the commencement of acolor change cycle. It is, of course, imperative that there be nopossibility of intermingling colors inadvertently.

The present invention provides a related group of color and solventcontrol air valves in series and so disposed that when, and only when,all of the color valves are closed, air will be supplied to the solventcontrol valve, causing solvent to enter the feed line to the spray gun.When the opertor determines that the feed line has been completelyflushed, as by visual observation or by the lapse of suflicient time, hethen opens the control air valve for the selected new color. Thismanipulation by itself will cut off the supply of air to the solventcontrol air valve because of the serial relation between the valves, andthe flow of solvent to the gun will stop and will be replaced by theflow of coating material fluid of the new color. The present inventionprovides, as an option, that the high pressure under which flushingtakes place will persist for a few seconds after the flow of the newcolor fluid commences so that the fluid conduits to the spray gun willbe filled rapidly with the new color fluid.

In one modification of the invention the cleaning and refilling of thesystem up to the spray gun is accomplished with the spray gun closed,and the cleaning fluid passes out to a waste tank. In this arrangementthe small fluid passage in the gun itself will retain some fluid of thecolor to be replaced. This fluid is flushed out very quickly by thesolvent remaining in the lines and by the new color when the gun isreopened. The capacity of the gun fluid passage may amount to only 1 cc.or 2 cc. and if the normal discharge rate of the spray gun is 150 cc.per minute, it can be seen that replacement of the old color by the newwill not cause a significant time delay. This puff of fluid at the endof the color change cycle in most cases can be directed betweensuccessive parts on a conveyor line without depositing on the conveyedarticles on either side.

The principal object of the invention is to provide an apparatus havingthe functional features discussed above.

Other objects and advantages of the invention will be apparent from thefollowing detailed description of a preferred embodiment thereof,reference being made to the accompanying drawings, in which:

FIGURE 1 shows a color change spray apparatus of this invention adaptedfor spraying three separate fluids, such as paints A and B and asolvent, through a single common spray gun, with the air, fluid andelectrical control systems schematically illustrated. In thismodification the spray gun is held open during a color change;

FIG. 2 shows diagrammatically an apparatus similar to FIG. 1, but inwhich the spray gun is held closed during a color change; and

FIGURE 3 shows diagrammatically an apparatus similar to FIG. 2, butembodying additional operating devices to improve performance undercertain conditions.

The diagrammatic representation of on-off air valves used in thedrawings is such that the normal connections through the valve body areindicated by full lines, while the alternate connections that areestablished by movement of the valve to its opposite position areindicated by dotted lines. Where a valve is normally operated manually,a push-pull button is indicated as connected to the movable valveelements. Where a valve is normally operated by a solenoid, the armatureof the solenoid is indicated as being directly connected to the movablevalve parts. In those instances in which the valve is shifted by aseparate pneumatic cylinder the associated piston and movable valveparts are shown as connected directly. These diagrammatic notations areused solely for simplification and are not intended to indicate theactual valve structures, or the structures of the activating means,which may be quite complex.

In the drawing a typical automatic spray gun is shown at 10 and includesa pneumatic cylinder 11 at the rear of the gun body having a piston 12the-rein which is directly connected to a fluid needle 13 of the spraygun. The needle 13 operates as a valve to open or close a central fluiddischarge passage 14 through which coating material is emitted foratomization. In the spray gun 10 atomizing air enters the gun body froma passage 15 and discharges from an annular orifice 15a immediatelyaround the fluid orifice in the cap portion of the spray gun. Theatomizing air is cont-rolled by an air valve 16 that is diagrammaticallyindicated as being carried by the fluid needle 13 and thus moved off itsseat by the piston 12 when the gun is turned on.

Fluid is supplied to the central fluid passage 14 of the spray gunthrough a conduit 17 and is held at a regulated pressure by a fluidregulating valve 18. During normal spraying, the fluid pressure ismaintained at a relatively low pressure, for example, 5 to 7 p.s.i. bycontrol air pressure from another control regulator valve 19. Theregulator valve 18 is such that its discharge pressure is a directfunction of the control air pressure imposed on its internal diaphragmby control regulator 19. Regulator 19 is manually adjustable so that theoperator can vary the normal fluid pressure at will.

The present invention is applicable to electrostatic ornon-electrostatic spray guns, but the invention is shown in connectionwith an electrostatic spray gun 10 supplied with high voltage from ahigh voltage power supply 20 connected to a suitable electrical source21. As is the usual practice, one side of the high voltage power supplyis grounded and the other side is taken to the gun through a highvoltage line 22. A high voltage switch 23 is interposed in the line 22and is normally held closed but may be opened when the holding airpressure is released.

In the diagrammatic system shown in the drawings the high voltage switch23 may be opened by movement of an air actuated cylinder 24 having itsplunger connected to a valve 25 such that movement of the plunger of theair cylinder 24 to the right, as shown, will cause the valve 25 to ventthe air cylinder of the high voltage switch 23, causing this switch 23to open by its spring pressure. The air cylinder 24 is in turncontrolled by a solenoid operated valve 26 which is normally in theupper or vented position as shown. When the circuit to the winding 27 ofthe solenoid operated valve 26 is energized, through closure of anormally open switch 28 controlled by an air cylinder 28a, the force ofthe solenoid 27 will pull the valve 26 closed, thus admitting air athigh pressure from a supply line 29 which will open the switch 23 andbreak the circuit to the high voltage line 22 and to the gun 10.

Air for the various control functions hereinafter described is takenfrom a regulated source 30. The regulation may be such as to cause airto enter the system at 60 p.s.i., in line 29, for example. From line 29,one branch line for the atomizing air connects, through a reducing valve31, to the atomizing air valve 16 within the gun 10 through line 15. Thereducing valve 31 is effective to reduce the air pressure from the line29 to a low value for atomization, such as 7-10 p.s.i.

The spray gun is supplied with fluid from several sources, A, B, C, byany suitable means. In the diagrammatic disclosure, the contents of thecontainers A, B, C, are placed under air pressure from source 30 througha branch line of the air supply line 29. The discharge from each of theseveral fluid containers A, B, C, goes respectively to a pneumaticallycontrolled valve 32A, 32B, 32C and thence into a common manifold 33 tothe fluid pressure regulator 18 adjacent the spray gun 10. This fluidregulator 18 normally permits fluid to flow to the spray gun 10 at areduced pressure of, for example, 5 to 7 p.s.i. because of the normal,low pressure air imposed thereon by the adjustable air regulator valve19.

Each of the pneumatically actuated valves 32A, 32B and 32C has arespective power cylinder 34, 35 and 36 to which air is admitted orexhausted from a respective connector line 37, 38, 39. Air to theseconnector lines 3739 is controlled by manually operated color controlvalves 40, 41, 42 respectively.

It will be seen that in the on or full line position (FIG. 1), the valve40 is connected such that air will flow from supply line 29, through abranch line 43, the valve 40, the connecting line 37, and the powercylinder 34 for the respective needle valve 32A, which is then opened.Fluid from container A will thus be pushed by air pressure from line 29through a feed line 44 through the open valve 32A into the paintmanifold 33 to the fluid regulator valve 18 adjacent the spray gun 10,through the passage 17 between the regulator valve 18 and the paintdischarge passage 14 within the gun.

It will be seen that when the paint A valve 40 is in its open position,no air can pass beyond this valve to either valve 41 or 42 above it inthe series. Further, it will be seen that the valve 41 or 42 can receiveair only when all valves beneath them in the series are in the closedposition. Thus it becomes impossible to charge two colors simultaneouslyinto the manifold 33 because only one of the power cylinders 34-36 canbe actuated to open the corresponding valve 32A-32C at one time.

In normal operation when the apparatus is spraying a single fluid uponobjects 45 sequentially presented to the spray gun on a moving conveyor,a control circuit including a photoelectric cell circuit 46, a solenoidoperated air valve 47, and an air valve 48 are operably connected to thepiston 12 and fluid needle 13 of the spray gun 10 to periodically blockthe flow of fluid and air from the gun 10 when no object 45 is beforethe gun pattern. The photoelectric cell circuit 46 is electricallyconnected to the electrical source 21 by leads 49 and 50 and ispositioned in the vicinity of the conveyor such that it is energized bythe presence of an object 45 (schematically shown in the drawings), whenthe object 45 or another such object is in the proper position on theconveyor, within the pattern of the spray gun 10. The output from theenergized photoelectric cell circuit 46 is connected to the winding 51of the solenoid operated air valve 47. When energized, the winding 51closes the air valve 47 to its lower, dotted line position whereby airat 60 p.s.i. flows from the supply line 29, through a branch line 52,the valve 47 and into the cylinder of the air valve 48, causing itspiston and plunger to close this valve to its upper, dotted lineposition. When the valve 48 is so closed, air at 60 p.s.i. flows throughthe valve 48, a branch line 53 to the air cylinder 11 in the gun 10,causing the piston 12 to withdraw and admit atomizing air to the gun andto open the discharge passage 14 thereof. As soon as the object 45 haspassed the photoelectric cell, the revenue sequence takes place and thegun 10 ceases to spray until another such object 45 is in the range ofthe pattern of the gun 10.

A bypass circuit, which may be operated manually or automatically, isprovided, which may be used to keep the operating piston 12 of the gun10 retracted, if desired, regardless of the condition of thephotoelectric cell circuit 46 and the pressure or absence of an article45 to be sprayed. As indicated diagrammatically in the drawings, amanually operated air valve 54 is connected through line 55 to the lowerport of the air valve 48 as shown. When the valve 54 is manually openedto its lower, dotted line position, air at 60 p.s.i. bypasses thesolenoid operated valve 47 and flows through the line 55, valve 48, andline 53 to the air cylinder 11 of the gun 10.

An important feature of the color change apparatus of this invention isthe system including the air operated switch 28, solenoid operated airvalve 26, the air operated voltage control valve 25 and an air operatedoverride air valve 56. The system including these components comprises ameans for overcoming the normal adjustment of regulator valves 18 and 19whereby fluid such as the solvent fluid from container C may be pushedthrough the control valve 32C, the manifold 33, the regulator 18, theline 17 and into the gun 10 at an increased pressure and velocity, thusreducing the time necessary for purging these lines of the terminatedfluid, paint A for example, prior to the initiation of spraying a secondfluid, paint B for example.

The air cylinder portion 28a of the air operated switch 28 is connectedto the outlet side of the manual color control valve 42 by a line 58whereby air pressure in the line 58 will push the piston of the aircylinder 28a to its upper, dotted line position and will close a pair ofnormally open contacts 59 to complete an electrical circuit from thepower source 21 to the solenoid winding 27. As previously explained, noair can flow to the manual solvent control valve 42 controlling the flowof solvent until both manual paint control valves 40 and 41 are closed.To terminate flow of a fluid such as paints A or B and to initiate theaccelerated purge cycle, the operator closes valve 40 or 41 and thuspermits air to flow through the valve 42, thus admitting air at 60p.s.i. to the line 58 and closing the electrical circuit to the winding27. The air valve 26, after the winding 27 is energized, is pulled toits lower (dotted line) position so that air flows through the valve 26to lines 60 and 61 and to the air cylinder 24 of valve 25. The followingsteps then occur simultaneously:

(1) Air in the line 61 forces the piston of an air cylinder 62downwardly, thus closing a normally open switch 63 to complete anelectrical circuit to the winding 51. This circuit, which is in parallelwith the circuit of the photoelectric cell 46, acts as a bypass to thephotoelectric cell circuit 46 and, in the manner previously explained,causes the gun 10 to remain on, or to be turned on regardless of thepresence or absence of an object 45 sensed by the photoelectric cellcircuit 46. The elfective disabling of the photoelectric cell circuit 46is necessary because, in this modification of the invention, it isdesirable to complete the solvent purge from the gun 10 when no objects45 are in front of the gun and with the gun 10 open.

(2) Movement of the piston of the air valve 24 to its right, dotted lineposition by air pressure from the valve 26 will move the valve 25 to theright to vent the air cylinder controlling the high voltage switch 23,causing the switch 23 to open and to break the high voltage chargingcircuit to the gun 10. This is desirable during the solvent purge periodto prevent the charged particles from leaving the spray path and beingdeposited on the grounded workpiece or grounded portions of sprayingapparatus. If desired a conventional grounded back contact can be placedon switch 23 to ground the gun during the time switch 23 is open.

(3) Air pressure in the line 60 operates the fluid override by movingthe piston in the air cylinder of the override valve 56 to the right,thus connecting the valve 56 to a line 64 with air at an intermediatepressure (30 p.s.i.), maintained by a regulator valve 65 from the line29. This air, passing under intermediate pressure to a line 66 through amanually operated two-way bypass valve 57 which is normally in its solidline, right hand position, enters the regulator valve 19 and opens theregulator valve 19, thus allowing control air at increased pressure toflow from the line 29, through a branch line 67, through the regulatorvalve 19 and a line 68 to the fluid pressure regulator valve 18 at ornear the gun 10. The regulator valve 18 is in turn opened, whereby thefluid from the container C will flow through the control valve 32C, themanifold 33, the regulator valve 18, the line 17 into the gun 10 atincreased pressure. By overriding the regulator valve 18, the solventpurge takes place at increased pressure and thus a much shorter time isrequired to purge the manifold 33 and subsequent lines of the terminatedfluid.

From the foregoing it will be seen that the flow of solvent through themanifold 33 and to the spray gun -10 will continue until such time asthe operator initiates the flow of the new color paint by pulling anappropriate paint control valve 40 or 41.

When purging of the system is completed, it is usually desirable todelay the inactivation of the override system for a short time after theinitiation of a new color cycle in order to permit the system to befilled at high pressure and to clear the system of the purging liquid.This delay is provided by any suitable device such as an electric timedelay switch 72 connected in parallel across the contacts 59 of the airoperated switch 28. When the operator initiates the flow of the newfluid by closing the manual change valve 41, for example, thesimultaneous venting of the line 58 causes the solvent control valve 32Cto close and also opens the contacts 59 of the air operated switch 28.The time delay device 72, however, will keep the circuit to the solenoid27 closed for a predetermined time after the switch contacts 59 areopened. Therefore, the override system will continue to operate andpaint from the control valve 32B will be forced through the manifold 33and subsequent lines at high pressure until the time delay device 72opens the circuit to the solenoid 27. Thus, in addition to theaccelerated purging cycle described, the system also includes anaccelerated refill cycle to reduce the time necessary for changing fromone color to another. Also, the spray gun 10 remains open and thevoltage remains off due to the continued presence of pressurized air inline 60.

From the foregoing, it will be understood that the flow of solventthrough the system will continue for an indefinite period of time andthat its termination is, in the form shown, manually controlled. It is,of course, desirable that the operator not terminate the flow of solventand the initiation of the new paint color too quickly. Therefore, thepresent invention provides an indicator that will alert the operator tothe passage of a minimum time during which the flow of solvent shouldpersist. In the form shown, the indicator is designated by the numeral70 and an interval timer 71 is actuated pneumatically by a branchconnection to line 58. The time interval begins to time out with theentry of air into line 58 at the beginning of the purge cycle. At theend of the timed interval, a valve 73 is shifted from vent position to aconnected position in which air enters from the main source line 29 to acylinder 74. A piston 76 is actuated thereby and in turn actuates theindicator 70 which may be either in the form of a flag, a light, or anyother alerting device. The interval timer 71 is automatically reset whenline 58 is vented at the end of the solvent cycle.

When the time delay device 72 times out, and the circuit around contacts59 is finally opened, the system will be'filled with paint of the newcolor and will be ready to spray under normal pressure. The solenoidcontrolled valve 26 will have returned to its normal, or vented positionshown in dotted lines in FIG. 1 and the air pressure will have beenremoved from the air cylinder 24, allowing the voltage control valve 25to move to its open position in which air passes from line 29 to the airoperated high voltage switch 23. As switch 23 closes, the voltage isrestored to the spray gun, and normal electrostatic spraying willproceed thereafter. At the same time, the air actuated automaticoverride valve 56 will move to its normal or vent position and theoverride pressure will be removed from line 66, allowing the airpressure control regulator 19 to return to its pre-set pressure. Thenormal regulator pressure will then be restored in the fluid regulator18, and the fluid pressure in line 17 leading to the spray gun will bewithin the normal range for satisfactory spraying. Thereafter the on-oifcontrol of the spray gun will revert to the automatic system including,for example, the photoelectric control circuit 46.

As it has been so far described, the present invention provides for theintroduction of air into the fluid override line 66 automatically, andonly during a color change cycle. However, the present invention isequally useful at any other time when it is only necessary totemporarily increase the pressure at which fluid is passed to the spraygun 10. In some instances, after prolonged operation, a spray gun 10will exhibit a tendency to clog or emit its spray in a pattern that isnot perfectly distributed. Under these circumstances, operation of thegun 10 even momentarily at a greatly increased pressure will frequentlyclear the system and cause it to return to normal operation. The presentinvention provides, for this purpose, the manually operated bypass valve57 for the fluid override air. The valve 57 in its normal position is inseries with the automatic override valve 56. When the valve 57 ismanually pulled from its full line to its dotted line position as shownin FIGURE 1, the series relationship to valve 56 is broken and aconnection is established by which air will pass from line 64 to theoverride air line 66. This will increase the control air pressure onregulator 19 and thus 0n the fluid pressure regulator valve 18, causingthe system to be filled with fluid of the same type as is then beingsprayed, but at much higher pressure. This will permit the operator toclear the gun or guns. The same manual control of the override airprovided by valve 57 also makes it possible to change from one color toanother directly at any time without going through the solvent purgingof the system by allowing a new color paint to displace a previous oneat high pressure.

The modification of the invention shown in FIGURE 2 of the drawingsdiffers from the modification previously described in that the colorchange or purging takes place with the spray gun 10 closed, rather thanopen. In reference to this modification, the same numerals have beenused to indicate parts of the system that are identical to the partspreviously described and shown in FIGURE 1. The modification may, ifdesired, eliminate the bypass for the photoelectric control circuit 46comprising air line 61 and the air operated switch 63. Thus, when thespray gun 10 is shut off in response to operation of the photoelectriccontrol circuit 46, it will remain off until this circuit 46 causes itto reopen.

A T-connection 76 is made to fluid line 17 at the point where it entersthe body of the spray gun 10 to connect into the interior fluid passage14. In the most simple form of this modification a fluid dump valve inthe form of a check valve 77 is inserted in the line leading from theT-connection 76 and the outlet from the check valve 77 is taken to anysuitable container, which is indicated as a waste drum W.

The check valve 77 is pre-set to open at a pressure in excess of thenormal pressure existing in line 17 during normal spraying. For example,if the upper range of the normal fluid pressure in line 17 is 7 pounds,then check valve 77 can be set to open in the direction of the wastecontainer at a pressure of 9 to 12 pounds. During the override cycle,while a color change is being made, fluid flows through line 17 at anincreased pressure and will thus pass out through the check valve 77since the spray gun 10 is now closed. All of the lines between line 17and the manifold 33, including the regulator valve 18, will be purgedand cleaned and the purging and cleaning fluid will pass out past checkvalve 77 to the container W. This will leave only the small quantity offluid trapped in the fluid passage 14 of the color that is beingdisplaced. The capacity of this interior passage 14 in the gun willusually amount to only 1 cc. or 2 cc. This small quantity of retainedfluid is readily displaced by any solvent remaining in line 17 anddisplaced by the next successive color.

If desired, provision can be made for opening the spray gun 10 inadvance of the time when the next part will be presented to the spraygun 10, or the automatic control comprising the photoelectric circuit 46may simply be relied upon to cause the gun 10 to reopen. The small puffof paint of the previous color can frequently be accepted on the newpart presented to the spray gun 10 without deteriorating the finish ofthe new part in any way. However, if it is felt that no paint whateverof the old color should be sprayed on the new part, then the spray gun10 should be opened in advance of the time when it would be normallyopened by the photoelectric control circuit 46 and the puff of paintdispersed in the space between parts on the conveyor.

In the sequence of operations of the apparatus shown in FIG. 2, let itbe assumed that the spray gun 10 is spraying paint on a part 45 from thecontainer containing paint A at normal spraying pressures, through valve32a as controlled by air valve 40. Under these circumstances,

9 the fluid pressure in line 17 will be from S to 7 p.s.i. and the airpressure in control line 68 will be the normal pressure required tomaintain the above-mentioned fluid pressure to the gun 10. When a colorchange cycle is to be initiated, the gun 10 will be turned off manuallyor automatically by the photoelectric control circuit 46 as the lastpart 45- of the paint A color passes out of the spray region of thespray gun 10. Thereupon, the operator will close air valve 40, causingthe paint A valve 32a to move to its seat. The several valves andswitches will then stand in the position shown in the drawings.

With paint A shut off, air will pass from lines 29 and 43 through valve40, through valve 41 and through valve 42 to line 58, as in themodification shown in FIG. 1. At the same time, air will pass throughbranch line 39 to valve 36 thus causing the solvent valve 320 to openand permit the flow of solvent or cleaner from container C into themanifold 33 and thence through regulator 18 into the fluid line 17leading to the spray gun. As soon as air appears in line 58, however,the air operated switch 28 is closed, closing the circuit to winding 27and causing electrically operated valve 26 to move to its open positionand impose an air pressure on the voltage control valve cylinder 24 andthus move valve 25 to vent position, opening switch 23 to shut 011 thevoltage on an electrostatic system and also to admit air pressure toline 60 which operates the automatic fluid override valve 56. When thevalve 56 moves to its open position, air flows from the line 64, at theintermediate pressure determined by regulator 65, through the valve 57and into the fluid pressure override line 66 to the regulator 19. Theregulator 19 thence imposes control air through line 68 on the fluidpressure regulator 18 at a higher pressure, raising the pressure offluid in line 17 leading to the spray gun.

The spray gun, meanwhile, remains closed since the photoelectric controlcircuit 46 has become inactive and has permitted valve 47 to move fromits open to its closed or vented position. This has taken the airpressure off the air operated valve 48 so that no air appears in thepneumatic cylinder 11 which controls the opening of the gun 10.

The higher pressure fluid in line 17, since it cannot pass the closedfluid valve 14 in the spray gun 10, passes out past check valve 77 andinto the waste container W. The flow of solvent continues until themanifold 33, the fluid chamber of the regulator 18 and the line 17 haveall been flushed at high pressure.

As in the form shown in FIG. 1, the operator will receive a signal fromindicator 70 at the end of a time period suflicient to completely purgethe paint-containing portions of the system ahead of the spray gun 10.When indicator 70 is actuated, the operator can change paint by openingvalve 41 controlling paint B, thus imposing an air pressure on line 38into cylinder 35 and opening valve 32!). When valve 41 controlling paintB has moved from its full line to its dotted line position to permit airto flow through the valve 41 to the control cylinder 35 for valve 32!),the air circuit to line 58 is broken, and air pressure from this line isvented through valve 41 to atmosphere. However, because of the timedelay imposed by the time delay element 72, the override pressure onregulator 19 will persist until the time delay device 72 times out. Thiscauses paint B to fill the system including the manifold 33, regulatorvalve 18 and line 17 at high pressure. There may be some spillage ofpaint out of line 17 onto the waste container but this need not persistfor any great length of time.

Assuming that no new part has yet come within the range of the spray gunand actuated the photoelectric control circuit 46, the operator canpurge the last one or two ccs. of paint from the spray gun 10 byoperating the manual control valve 54 and causing control air to flowthrough the branch line 52, the valve 54, the valve 48 and into the line53 running to the gun air cylinder 11.

This moves the gun piston 12 back and opens the gun 10. A small puff ofpaint of the paint A color will be forced out of the system ahead of thenew color. If valve 54 is then manually returned to its closed, upperposition shown in full lines in the drawings, the gun 10 will not againoperate until such time as a part 45 is within the operating range ofthe gun. Thereafter, the system will spray paint of the new color fromcontainer B through valve 32b into the manifold 33, through theregulator 18 and the line 17 at the normal spraying pressure, since theoverride pressure in line 66 will have returned to normal. The normalpressure appearing in line 17 is insufficient to open check valve 77 sothat paint from line 17 will pass through the normal fiuid passage 14 inthe gun 10 whenever the fluid passage is opened.

FIGURE 3 shows a system embodying two important features that areapplicable to the embodiments of the invention disclosed in FIGS. 1 and2. The system there shown makes provision for spraying coating materialsof widely varying viscosity by the inclusion of individual pressureregulators 100, 101 and 102 in series with the main regulator controlvalve 19 which governs the pressure applied to the fluid regulator valve18.

Each of the pressure regulator valves 100, 101 and 102 is connected inan identical air circuit so that a description of one will suflice forthe others. In FIG. 3, it will be seen that whenever air is applied tothe paint valve operating cylinder 35 through line 38, to open paintvalve 32b, air also enters a branch connection 104 to the pressureregulator valve 101. The pressure of this air is the same as thepressure in the main supply line 29 (less small losses in the valves).Regulator 101 drops this pressure to a smaller pressure determined byits setting and applies the smaller pressure to a line 105 leading pastan outwardly opening check valve 106 to an air manifold 107 and thenceby line 108 to the control chamber of the main regulator valve 19. Thesetting OLf the main regulator valve 19 is thus changed and, as aconsequence, the pressure on the fluid regulator valve 18 is adjusted.if, for example, fluid has been sprayed at relatively high pressure dueto a high viscosity, valve 18 will have been adjusted by valve 19 tocause the passage of high pressure fluid to the spray gun 10. Upon theintroduction of a lower viscosity paint by the opening of valve 32a, forexample, it will be desirable to lower the fluid pressure. This isaccomplished automatically by preselecting the setting of regulatorvalve 102 in series with the control cylinder for valve 32a to cause alower pressure to be imposed on the main regulator valve 19, and thus alower control pressure on the fluid pressure regulator valve 18. Upon aclosure of valve 32a and a reopening of valve 3212 the pressureconditions to the main regulator will revert to those determined by thesetting of regulator 101.

This modification of the invention shown in FIG. 3 also adds an airactuated dump valve 110 in the passage to the Waste container W,replacing check valve 77 shown in FIG. 2. The dump valve is openedduring a color change operation by an air cylinder 111 that receives airwhenever a color change operation starts and air is introduced into line60 leading to the fluid pressure override valve 56. The connectionbetween line 60 and cylinder 111 is designated 112. Thus, the dump valve110 will be held open during that part of the color change cycle inwhich flushing material or solvent is introduced and also during fillingof the new color paint by reason of the operation of the time delaydevice 72.

As in the (form shown in 'FIG. 2, the spray gun 10 is closed during thetime the system is flushed, but in this instance the spray gun isdeliberately opened during the last portion of the color changeoperation. To accomplish this, an air operated spray gun control valve115 is provided, the position of which changes when the override systemis operating only under the influence of the time delay device 72. Inits dotted line position, the valve 115 will admit air under pressurefrom line 60 (whenever present) to the spray gun cylinder 12 to open thegun. In its second or vent position, shown in full lines, the spray guncylinder 11 will be vented through line 53, valve 48, valve 54 and valve115.

The valve 115 is actuated to the vent position whenever high pressureair apears in line 58 at the start of the color change operation whenthe operator has turned all of the paint valve control devices 40 and 41off and opened the solvent control device 42. Thus the spray gun willimmediately turn oflf. When the operator pulls one of the paint controldevices to open position, the pressure in line 58 is dissipated so thatvalve 115 moves to its dotted line position and connects line 60, inwhich there is still pressurized air, to the gun control cylinder 11.The spray gun then opens and will remain open so long as line 60contains air under pressure. This period is established by the timedelay device 72. It will thus be seen that valve 115 operates to holdthe spray gun closed during a first part of the color change operationand to open the gun during the second part of the operation.

Under these conditions at the second part of the color change operation,the spray gun and the dump valve 110 are both open and the lines 33, thebody of the fluid regulator 18 and line 17 are being filled with paintof the selected new color. Since these lines have been filled withsolvent, the solvent is displaced rapidly at override pressure, withpart passing out of the spray gun 10 and part passing through the dumpvalve 110. That portion of the solvent passing through the spray gundisplaces the paint of the initial color trapped in the gun body. Thisflow persists until the time delay device 72 times out, opening thecircuit to solenoid 27 and shifting valve 26 to dissipate the pressurefrom line 60. Thereupon both the pump valve 110 and the spray guncylinder 11 will be vented through valve 26 and the gun will close. Thetime established by the time delay device 72 is selected to assurefilling the system with paint of the new color.

:Once the automatic air actuated valve 115 moves to vent position,control of the opening and closing of the spray gun by its cylinder 11reverts to the air operated valve 48 previously described.

While the invention has been described in conjunction with a specificform and disposition of parts using a single spray gun, it is to beunderstood that the control appara tus may be used to control aplurality of individual guns connected in parallel and positioned tosimultaneously spray all surfaces of large and complex objects. In sucha multiple installation, each gun may be provided with its own separateregulator valve 18 and control regulator 19, with pneumatic and coatingfluid supply lines from a common control apparatus. Various othermodifications and changes may be made without departing from the scopeof the invention as defined in the appended claims.

What I claim is:

1. In a control for a spray apparatus in which fluid material is fed toand discharged from a spray gun, said spray gun having a fluid supplypassage, and having a pneumatic means to turn said spray gun on and ofl,first control means to actuate said pneumatic means to the on position,a fluid pressure regulator valve interposed in said supply passage, thedischarge pressure of said regulator valve being responsive to a controlair pressure, means to maintain a relatively low control air pressure onsaid regulator valve and thus a relatively low fluid pressure in saidsupply passage during normal spraying, override means to impose arelatively high control air pressure on said regulator valve and thus arelatively high fluid pressure in said supply passage during otheroperation of said spray gun, and common means to actuate said overridemeans and said first control means to the on position, whereby materialin said fluid supply passage may be rapidly replaced irrespective ofsaid first control means.

2. In a control for a spray apparatus in which fluid material is fed toand discharged from a spray gun, said spray gun having a fluid supplypassage, and having a pneumatic means to turn said spray gun on and off,first control means responsive to the presence of an article to besprayed to actuate said pneumatic means to the on position and toactuate said pneumatic means to the off position in the absence of anarticle to be sprayed, a fluid pressure regulator valve interposed insaid supply passage, the discharge pressure of said regulator valvebeing responsive to a control air pressure, means to maintain arelatively low control air pressure on said regulator valve and thus arelatively low fluid pressure in said supply passage during normalspraying, override means to impose a relatively high control airpressure on said regulator valve and thus a relatively high fluidpressure in said supply passage during other operation of said spraygun, and common means to actuate said override means and said firstcontrol means to the on position regardless of the presence or absenceof an article to be sprayed, whereby material in said fluid supplypassage may be rapidly replaced irrespective of said first controlmeans.

3. In a control for a spray apparatus in which fluid is fed to anddischarged from a spray gun, said spray gun having a fluid supplypassage, a fluid pressure regulator valve interposed in said supplypassage, the discharge pressure of said regulator valve being responsiveto a control air pressure, means to maintain a relatively low controlair pressure on said regulator valve and thus a relatively low fluidpressure in said passage during normal spraying, a fluid manifold havinga discharge port connected to said supply passage, said manifold havingan inlet port for each of a plurality of fluids, a separate valve meansinterposed between each fluid source and a respective inlet port of saidfluid manifold and having open and closed positions, a separate operatorfor each of said valve means to move said separate valve means to openor closed positions, interlocking means to prevent actuation to the openposition of more than one of said separate valve means at any one time,an override means to impose a relatively high control air pressure onsaid regu lator valve and thus a relatively high pressure in said fluidsupply passage during other operation of said spray gun, and aninterconnection between said separate valve operators and said overridemeans so arranged that said override means is operable only when apredetermined one of said separate valve means is in open position.

4. The control for a spray apparatus as defined in claim 3 and a secondoverride means operable irrespective of the positions of said separatevalve means whereby a relatively high control air pressure can beimposed at any time on said regulator valve to cause a relatively highpressure in said fluid supply passage during other operation of saidspray gun.

5. The control for a spray apparatus defined in claim 3, and meansincluding a time delay means to maintain said relatively high pressurein said fluid supply passage for a predetermined time after saidseparate operators have been positioned to close said predetermined oneof said separate valve means.

6. The control for a spray apparatus defined in claim 3 in which saidoverride means is pneumatically actuated and in which said separateoperators include pneumatic valves connected in series in a pneumaticcircuit between said override means and a source of air pressure wherebyoperating air can pass to said override means only when said separateoperators are positioned to open said predetermined one of said separatevalve means.

7. In a spraying apparatus in which a plurality of fluids areselectively fed to and discharged from a comman spray gun, thecombination of a fluid pressure regulator valve adjacent the spray gunand discharging fluid thereinto at a relatively low pressure duringnormally continuous spraying operation, a fluid manifold having adischarge port connected to said fluid pressure regulator valve and aninlet port for each of said plurality of fluids, a separate valve meansinterposed between each fluid source and a respective inlet port of saidmanifold and having open and closed positions, interlocking means toprevent actuation to the open position of more than one separate valvemeans at any one time, one of said separate valve means being operableto control the flow of a cleaning fluid to said manifold, saidinterlocking means being constructed and arranged to cause cleaningfluid to flow to said manifold when all of the remainder of said valvemeans are closed, and override means to increase the discharge pressureof said regulator valve and of said fluid at least whenever saidcleaning fluid valve is open.

8. In a spraying apparatus as defined in claim 7 and means to indicateduration of the time of opening of said cleaning fluid valve.

9. In a control for a spray apparatus in which fluid material is fed toand discharged from a spray gun, pneumatic means to turn said spray gunon and off, said spray gun having a fluid supply passage, a fluidpressure regulator valve interposed in said supply passage, thedischarge pressure of said regulator valve being responsive to a controlair pressure, means to maintain a relatively low control air pressure onsaid regulator valve and thus a relatively low fluid pressure in saidsupply passage during normal spraying, override means to impose arelatively high control air pressure on said regulator valve and thus arelatively high fluid pressure in said supply passage during otheroperation of said spray gun, and a by-pass means connected to saidsupply passage and opened when said relatively high fluid pressure isimposed on said supply passage and when said pneumatic means has turnedsaid spray gun off.

10. The control defined in claim 9 in which said bypass means includes avalve-controlled passage connected immediately adjacent said spray gun.

11. In a control for a spray apparatus in which fluid is fed to anddischarged from a spray gun, said spray gun having a fluid supplypassage, a fluid pressure regulator valve interposed in said supplypassage, the discharge pressure of said regulator valve being responsiveto a control air pressure, means to maintain a relatively low controlair pressure on said regulator valve and thus a relatively low fluidpressure in said passage during normal spraying, a fluid manifold havinga discharge port connected to said supply passage, said manifold havingan inlet port for each of a plurality of fluids, a separate valve meansinterposed between each fluid source and a respective inlet port of saidfluid manifold and having open and closed positions, a separate operatorfor each of said sep arate valve means to move said separate valve meansto open or closed positions, interlocking means to prevent actuation tothe open position of more than one of said separate valve means atanyone time, pneumatic means to open and close said spray gun, anoverride means to impose a relatively high control air pressure on saidregulator valve and thus a relatively high pressure in said fluid supplypassage, a series interconnection between said separate valve and saidoverride means to introduce air under pressure in a control line forsaid override means when only a predetermined one of said separate valvemeans is in open position, and a dump valve in said fluid supply passagehaving an open and closed position, and a control for said dump valveoperable to open said dump valve whenever air under pressure isintroduced into said control line for said override means.

12. The control for a spray gun as defined in claim 11, and meansincluding a time delay means to maintain said override means inoperation and said relatively high pressure in said fluid supply passagefor a predetermined time after said separate operators have beenpositioned to close said predetermined one of said separate valve meansand the air under pressure in said control line has been dissipated.

13. The control for a spray gun as defined in claim 12, and a controlfor said pneumatic gun opening means including a valve operating toclose said spray gun when air under pressure is introduced into saidcontrol line for said override means.

14. The control for a spray gun as defined in claim 12, and a controlfor said pneumatic gun opening means including a valve operating toclose said spray gun when air under pressure is introduced into saidcontrol line for said override means and to open said spray gun when theair under pressure is said control line has been dissipated.

15. In a control for a spray apparatus in which fluid is fed to anddischarged from a spray gun, said spray gun having a fluid supplypassage, a fluid pressure regulator valve interposed in said supplypassage, the discharge pressure of said regulator valve being responsiveto control air pressures to maintain relatively low fluid pressures insaid passage during normal spraying a plurality of airregulator valvesassociated with a plurality of separate fluid valves whereby actuationof each of said separate fluid valves causes its respectiveair-regulator valve to control said fluid regulator valve to etfect adifferent spray pressure for said spray gun, a fluid manifold having adischarge port connected to said supply passage, said manifold having aninlet port for each of a plurality of fluids, said separate valve meansbeing interposed between each fluid source and a respective inlet portof said fluid manifold and having open and closed positions, a separateoperator for each of said separate valve means to move said separatevalve means to open or closed positions, interlocking means to preventactuation to the open position of more than one of said separate valvemeans at any one time, an override means to impose a relatively highcontrol air pressure on said fluid regulator valve and thus a relativelyhigh pressure in said fluid supply passage during other operation ofsaid spray gun, and an interconnection between said separate valveoperators and said override means so arranged that said override meansis operable only when a predetermined one of said separate valve meansis in open position.

References Cited UNITED STATES PATENTS 3,121,024 2/1964 Wampler et al.118-2 3,145,930 8/1964 Herklotz 23915 WALTER A. SCHEEL, PrimaryExaminer.

J. P. MCINTOSH, Assistant Examiner.

US. Cl. X.R. 1l89, 302; 239-70 g;;g UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION v Patent No. },50 ,O92 Dated June 17, 1969Inventor (s) Erhard KOCk It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 12, line 39, after "said" insert separate SIGNED ANU SEALED OCT 2l 1969 wmxm E. suaunm, m. Amflfi g Offioer Gomissioner or Yatanta

